1. Field of the Invention
The present disclosure relates to an image processing apparatus for forming an image with use of a long connected head constructed by connecting a plurality of recording heads, each of which includes a plurality of recording element arrays arranged substantially in parallel, in a direction of the recording element arrays, and a method for controlling the image processing apparatus.
2. Description of the Related Art
An image forming apparatus, which is used as an output apparatus for, for example, electronic apparatuses including a computer, a word processor, and the like, is configured to record an image (including a character, a symbol, and the like) on a recording medium such as a sheet. An inkjet type image forming apparatus (an inkjet image forming apparatus) forms an image by discharging ink from recording elements toward a recording medium with use of a recording head.
As one type of the inkjet image forming apparatus, there is a so-called full line type inkjet image forming apparatus, which includes a recording head having a recording width corresponding to a width of a recording medium and forms an image while involving only a movement of the recording medium in a conveyance direction. For the full line type inkjet image forming apparatus, the recording medium is set at a predetermined position, and a recording operation is performed while the recording medium is conveyed. For the recording head used in the above-described full line type image forming apparatus, it is currently difficult to process all inkjet recording elements throughout an entire width of the recording area of the recording medium without a defect. For example, realizing recording with a resolution of 1200 dpi on a sheet of an A3 size by the full line type recording apparatus requires formation of approximately 14000 recording elements (a recording width of approximately 290 mm) at the full line type recording head. Processing such a large number of recording elements entirely without a single defect involves a difficulty in manufacturing processes. Further, even if it is possible to manufacture this recording head, this manufacturing should lead to a low yield rate and a significant increase in manufacturing cost.
For the above-described reasons, a so-called connected head is proposed as the full line type recording head. The connected head is a recording head constructed by connecting a plurality of recording heads (recording chips), each of which includes a plurality of recording element arrays arranged substantially in parallel, in such a manner that recording element arrays partially overlap. The recording element arrays each include a plurality of arrayed recording elements. In other words, it is possible to realize a head extending throughout an entire width of a recording area by arranging a plurality of short recording heads so as to connect them in a direction along which recording elements are arranged.
This connected head has a problem of a high possibility of generation of a boundary streak. The boundary streak is deterioration of an image quality that is generated at a portion where ends of recording element arrays are adjacent to each other between the recording heads. This is caused due to, for example, differences in attachment and inclination between the recording element arrays, and a variation in conveyance of a recording medium. Therefore, Japanese Patent Application Laid-Open No. 2010-17977 discusses a method for controlling an exclusive relationship according to a distance between recording element arrays for a same color on different recording heads for each dot pattern to be formed by an overlap portion (a connection portion) of recording heads.
However, the method discussed in the above-described Japanese Patent Application Laid-Open No. 2010-17977 may be unable to necessarily appropriately control an exclusive relationship between dot patterns to be formed by the respective recording element arrays. This problem occurs in an image forming apparatus that uses recording heads each including a plurality of recording element arrays for a same color as the full line type recording head. In this case, the recording element arrays for a same ink exist on both a same head and a different head. Therefore, an excellent dot layout may be unable to be acquired even by controlling the exclusive relationship with use of the distance, like the method discussed in Japanese Patent Application Laid-Open No. 2010-17977. This is because the possibility of generation of a boundary streak between two recording element arrays disposed on a same head is different from that between two recording element arrays disposed on different heads.